1 //===- Main.cpp - Top-Level TableGen implementation -----------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // TableGen is a tool which can be used to build up a description of something, 10 // then invoke one or more "tablegen backends" to emit information about the 11 // description in some predefined format. In practice, this is used by the LLVM 12 // code generators to automate generation of a code generator through a 13 // high-level description of the target. 14 // 15 //===----------------------------------------------------------------------===// 16 17 #include "llvm/TableGen/Main.h" 18 #include "TGParser.h" 19 #include "llvm/ADT/StringExtras.h" 20 #include "llvm/Support/CommandLine.h" 21 #include "llvm/Support/FileSystem.h" 22 #include "llvm/Support/MemoryBuffer.h" 23 #include "llvm/Support/ToolOutputFile.h" 24 #include "llvm/TableGen/Error.h" 25 #include "llvm/TableGen/Record.h" 26 #include <algorithm> 27 #include <cstdio> 28 #include <system_error> 29 using namespace llvm; 30 31 static cl::opt<std::string> 32 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"), 33 cl::init("-")); 34 35 static cl::opt<std::string> 36 DependFilename("d", 37 cl::desc("Dependency filename"), 38 cl::value_desc("filename"), 39 cl::init("")); 40 41 static cl::opt<std::string> 42 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-")); 43 44 static cl::list<std::string> 45 IncludeDirs("I", cl::desc("Directory of include files"), 46 cl::value_desc("directory"), cl::Prefix); 47 48 static cl::list<std::string> 49 MacroNames("D", cl::desc("Name of the macro to be defined"), 50 cl::value_desc("macro name"), cl::Prefix); 51 52 static int reportError(const char *ProgName, Twine Msg) { 53 errs() << ProgName << ": " << Msg; 54 errs().flush(); 55 return 1; 56 } 57 58 /// Create a dependency file for `-d` option. 59 /// 60 /// This functionality is really only for the benefit of the build system. 61 /// It is similar to GCC's `-M*` family of options. 62 static int createDependencyFile(const TGParser &Parser, const char *argv0) { 63 if (OutputFilename == "-") 64 return reportError(argv0, "the option -d must be used together with -o\n"); 65 66 std::error_code EC; 67 ToolOutputFile DepOut(DependFilename, EC, sys::fs::F_Text); 68 if (EC) 69 return reportError(argv0, "error opening " + DependFilename + ":" + 70 EC.message() + "\n"); 71 DepOut.os() << OutputFilename << ":"; 72 for (const auto &Dep : Parser.getDependencies()) { 73 DepOut.os() << ' ' << Dep.first; 74 } 75 DepOut.os() << "\n"; 76 DepOut.keep(); 77 return 0; 78 } 79 80 int llvm::TableGenMain(char *argv0, TableGenMainFn *MainFn) { 81 RecordKeeper Records; 82 83 // Parse the input file. 84 ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr = 85 MemoryBuffer::getFileOrSTDIN(InputFilename); 86 if (std::error_code EC = FileOrErr.getError()) 87 return reportError(argv0, "Could not open input file '" + InputFilename + 88 "': " + EC.message() + "\n"); 89 90 // Tell SrcMgr about this buffer, which is what TGParser will pick up. 91 SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc()); 92 93 // Record the location of the include directory so that the lexer can find 94 // it later. 95 SrcMgr.setIncludeDirs(IncludeDirs); 96 97 TGParser Parser(SrcMgr, MacroNames, Records); 98 99 if (Parser.ParseFile()) 100 return 1; 101 102 // Write output to memory. 103 std::string OutString; 104 raw_string_ostream Out(OutString); 105 if (MainFn(Out, Records)) 106 return 1; 107 108 // Always write the depfile, even if the main output hasn't changed. 109 // If it's missing, Ninja considers the output dirty. If this was below 110 // the early exit below and someone deleted the .inc.d file but not the .inc 111 // file, tablegen would never write the depfile. 112 if (!DependFilename.empty()) { 113 if (int Ret = createDependencyFile(Parser, argv0)) 114 return Ret; 115 } 116 117 // Only updates the real output file if there are any differences. 118 // This prevents recompilation of all the files depending on it if there 119 // aren't any. 120 if (auto ExistingOrErr = MemoryBuffer::getFile(OutputFilename)) 121 if (std::move(ExistingOrErr.get())->getBuffer() == Out.str()) 122 return 0; 123 124 std::error_code EC; 125 ToolOutputFile OutFile(OutputFilename, EC, sys::fs::F_Text); 126 if (EC) 127 return reportError(argv0, "error opening " + OutputFilename + ":" + 128 EC.message() + "\n"); 129 OutFile.os() << Out.str(); 130 131 if (ErrorsPrinted > 0) 132 return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n"); 133 134 // Declare success. 135 OutFile.keep(); 136 return 0; 137 } 138